Angioplasty devices are used to treat a wide variety of conditions and to perform a wide variety of procedures, including without limitation: congenital or acquired stenoses or obstructions; percutaneous aspiration thromboembolectomy; cerebral embolization; congenital or acquired obstruction or stenosis of the aorta, renal, coronary, pulmonary, iliac, femoral, popliteal, peroneal, dorsalis pedis, subclavian, axillary, brachial, radial, ulnar, vertebral, cerebral and/or cerebellar artery or any other accessible artery or their ramifications; congenital or acquired obstruction or stenosis of the superior vena cava, inferior vena cava, common iliac, internal iliac, external iliac, femoral, greater saphenous, lesser saphenous, posterior tibial, peroneal, popliteal, pulmonary, coronary, coronary sinus, innominate, brachial, cephalic, basilic, internal jugular, external jugular, cerebral, cerebellar, sinuses of the dura mater and/or vertebral vein or any other accessible vein or their ramifications; atheromatous lesions of any graft or its ramifications; obstructions or stenoses of connections between and among grafts, veins, arteries, organs and ducts; vena caval bleeding; congenital or acquired intracardiac obstructions, stenoses, shunts and/or aberrant communications; congenital or acquired cardiovascular obstructions, stenoses and/or diseases; infusion of thrombolytic agents; thromboembolic phenomena; diagnostic catheterization; removal of clots; intrahepatic and/or extrahepatic biliary ductal obstructions (e.g., stones, sediment or strictures); intravascular, intracardiac and/or intraductal foreign bodies; renal dialysis; congenital and acquired esophageal and/or gastrointestinal obstructions and/or stenoses; non-organized atheromata; dialysis fistula stenosis; ruptured cerebral aneurysm; arterio-arterial, arteriovenous and/or veno-venous fistulae; ureteral obstructions (e.g., stones, sediment or strictures); fibromuscular dysplasia of the renal artery, carotid artery and/or other blood vessels; and/or atherosclerosis of any accessible artery, vein or their ramifications. Such procedures may be performed in both humans and in other applications.
Conventional angioplasty devices generally consist of a catheter containing a balloon-like member that is inserted into an occluded vessel. Expansion of the balloon at the obstruction site crushes the obstruction against the interior lining of the vessel. When the balloon is retracted, the obstruction remains pressed against the vessel wall and the effective diameter of the vessel through which fluid may flow is increased at the site of the obstruction. Examples of angioplasty devices incorporating a balloon are shown in U.S. Pat. Nos. 4,646,742; 4,636,195; 4,587,975; and 4,273,128.
Other conventional angioplasty devices have been developed that incorporate expandable meshes or braids, drilling or cutting members, or lasers as a means for removing an obstruction. Examples of these angioplasty devices are illustrated by U.S. Pat. Nos. 4,445,509; 4,572,186; 4,576,177; 4,589,412; 4,631,052; 4,641,912; and 4,650,466.
Many problems have been associated with these angioplasty devices. Perhaps the most significant problem is the creation of particulate matter during the obstruction removal procedure. Recent ex vivo studies have demonstrated that huge numbers of emboli are produced on inflation and on deflation of the angioplasty balloon during dilation of a stenotic lesion. See Ohki T. Ex vivo carotid stenting, (Presentation) ISES International Congress XI, Feb. 11, 1998. These particles are released into the fluid flowing through the vessel and can lead to emboli, clots, stroke, heart failure, hypertension and decreased renal function, acute renal failure, livedo reticularis and gangrene of the lower extremities, abdominal pain and pancreatitis, cerebral infarction and retinal emboli, tissue injury, tissue death, emergency bypass surgery, death and other undesirable side effects and complications. Regardless of the type of angioplasty device used, a substantial number of particles will be generated.
Even very small particles can cause significant harm. The cross-sectional diameter of normal capillaries varies for different parts of the body and may be comprised of vessels as small as 2.0-3.5μ for very thin capillaries or 3.5-5.0μ for moderately thin capillaries. Accordingly, any particles that exceed these sizes can lodge inside the vessel. Furthermore, in the case of the heart, approximately 45% of the capillaries are closed at any given time, so that any particle, no matter how small, dislodged into this organ is liable to capture. Accordingly, it has become apparent that distal embolization presents a formidable threat.
One partial solution to the above-noted problems is disclosed in U.S. Pat. No. 4,794,928 to Kletschka. This angioplasty device incorporates a trap/barrier for trapping and removing particles that break away from the treatment sight. This device is desirable because it can prevent physiologically significant particles from escaping from the obstruction site, thus preventing the occurrence of unfavorable side effects from angioplasty treatment and procedures. One problem with this design, however, is that it is difficult to simultaneously provide an angioplasty device that is small enough to be used in very small and medium sized arteries, and/or in severely occluded vessels (i.e., vessels having a 90% or greater stenosis), and that has sufficient suction to remove the particulate matter.
Another partial solution to the above noted problems uses multiple catheters. These devices require that the doctor first deliver a “blocking” catheter to the target region such that its occlusion balloon is distal to the treatment site. The doctor then loads a second “balloon” catheter over the blocking catheter and performs the angioplasty procedure. The second catheter is then removed and a third catheter is loaded in its place over the blocking catheter. The third catheter can be used to aspirate blood from the treatment site. One problem with this design, however, is that it does not provide a means for capturing particles that are too large to fit within the suction lumen. Another problem is that this design requires a complex and relatively lengthy operational procedure, which can lead to neurological complications. In addition, particulate matter may also escape or be pulled from the treatment site when the catheters are switched and when the blocking balloon is deflated. Even when combined with suction, the risk exists that particles too large to be removed through the suction conduit will be delivered distally from the forward thrust of the blood flow as the blocking balloon is deflated.
Still another partial solution uses a porous hood that allows blood to pass. The hood, attached to the guidewire with struts, is held in a collapsed state within the angioplasty catheter. The hood deploys when pushed beyond the tip of the restraining catheter. Withdrawing the hood within the catheter closes the trap. These devices, however, do not provide suction and require multiple catheters. In addition, small particles may pass through the porous hood.
FIG. 1 illustrates the problems associated with obtaining the size of conduits necessary to do just the desired insertion, inflation, and suction tasks. FIG. 1 is a cross section of a five French catheter 10. A standard, 150 centimeter long, catheter may need a suction lumen 12 with a diameter of about 0.025 inches in order provide sufficient suction at its operational end to cope with debris released from a large atheromatous plaque. The catheter may also require an inflation/deflation lumen 14 with a diameter of about 0.015 inches to inflate an angioplasty balloon and a centered guidewire lumen 16 having a diameter of about 0.035 inches to position the device. As can be seen, these lumens significantly interfere with each other. An additional mechanism to open and close a blocking/capturing device will further encroach on allocatable space.
Clearly, there is a need for an improved angioplasty device for use in small diameter and/or severely occluded vessels that can prevent substantially all physiologically significant particles from escaping from the obstruction site, thus preventing the occurrence of unfavorable side effects from the angioplasty treatment and procedures. There is also a need for a small diameter angioplasty device that can provide aspiration, blocking, and capturing capabilities. In addition, there is a need for an improved particle trap that can prevent substantially all physiologically significant particles from escaping from the obstruction site and that can fit within, and be actuated by, a small diameter catheter bundle.